There were only three candidates on the stage in the latest Democratic presidential debate, but each had plenty of big moments as they argued about taxes on the middle class, intervention abroad and the safety of their campaign data. Here are the most memorable, important and explosive moments from Saturday's ABC News debate:

1. Sanders apologizes for data breach

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Right out of the gate, Sen. Bernie Sanders apologized for this week's data breach, in which Sanders campaign staffers improperly accessed voter data from Hillary Clinton's campaign. And Clinton accepted his apology.

“Yes, I apologize,” Sanders said. “Not only do I apologize to Secretary Clinton, and I hope we can work on an independent investigation, I apologize to my supporters.”

“I very much appreciate that comment, Bernie," Clinton said. "It is important that we go forward on this. I know that you now have your data back and there has been an agreement for an independent inquiry into what did happen. ... Now that ... we've resolved your data, we've agreed on an independent inquiry, we should move on. Because I don't think the American people are all that interested in this."

2. Clinton: Trump is ISIS' ‘best recruiter’

All the candidates pivoted to attack Donald Trump again and again during the debate, repeatedly using him as a foil. At one point, Clinton contrasted Trump’s rhetoric on fighting Islamic terrorists with former President George W. Bush's repeated statements that the United States was not at war with all Muslims.

“George W. Bush has done this, I give him credit,” Clinton said before saying that Trump is becoming ISIS’ best recruiter. "They are going to people showing videos of Donald Trump insulting Islam and Muslims in order to recruit more radical jihadists."

3. Sanders raises Iraq War vote on foreign policy

After Clinton defended instituting a no-fly zone over Syria, Sanders brought up Clinton's vote to go to war in Iraq over a decade ago to contrast their foreign policies.

"Our differences are fairly deep on this issue," Sanders said. "We disagreed on the war in Iraq. ... I say this with due respect, I worry that Secretary Clinton is too much into regime change and too aggressive without knowing what the unintended consequences could be." After bringing up Iraq again as well as Libya, Sanders continued: "Yes, we could get rid of [Syrian President Bashar] Assad tomorrow, but that would create another political vacuum that would benefit ISIS. ... Getting rid of dictators is easy, but you have to think of what will come after."

Clinton shot back: “With all due respect, senator, you voted for regime change in Libya. ... All of these are very difficult issues. I know that, I've been dealing with that for a very long time.”

4. Clinton: U.S. 'where we need to be' on ISIS

Clinton sounded an optimistic note on the country's ability to handle the threat of ISIS, also known as the Islamic State: "We now finally are where we need to be. We have a strategy and a commitment to go after ISIS, which is a danger to us as well as the region."

The comments followed talk about the challenge of Syria: "I think it's fair to say, Assad has killed, by last count, about 250,000 Syrians. The reason we are in the mess we're in, that ISIS has the territory it has, is because of Assad. I advocated arming the moderate opposition back in the day when I was still secretary of state, because I worried we would end up exactly where we are now. And so, when we look at these complex problems, I wish it could be either/or. I wish we could say yes, let's go destroy ISIS and let's let Assad continue to destroy Syria, which creates more terrorists, more extremists by the minute. No. We now finally are where we need to be."

5. O'Malley thunders away on guns to contrast with opponents

Martin O’Malley jumped in, talking over the moderators, to hit both Sanders and Clinton on guns. While touting his gun control record in Maryland, O'Malley called both of them inconsistent and squishy on the issue.

“Secretary Clinton changes her position on this every election year,” O’Malley said. “Look, what we need is not more polls, we need more principles.” He continued, saying both Clinton and Sanders exemplified the "flip-flopping political approach of Washington.”

The other two Democratic candidates didn’t take that lightly. “Whoa, whoa, let’s tell the truth here,” Sanders said, with Clinton adding “Yeah, let’s tell the truth here.” Both said O'Malley misrepresented them, with Sanders touting his past campaigns in Vermont and Clinton ticking off her support for the Brady Bill and closing loopholes for gun sellers.

6. Clinton calls for gun control as part of terrorism response

Asked about how to handle the threat of domestic and lone-wolf terrorism after the San Bernardino, California, attack, Clinton brought gun control into the conversation: "If you only think about the coalition abroad, you’re missing the point because we need a coalition at home. … Arming more people — to do what? — I think is not the appropriate response to terrorism."

Once again, Clinton hit out at Trump: "I worry greatly that the rhetoric coming from Republicans, particularly Donald Trump, is sending a message to Muslims in the United states and around the world that there is … a war against Islam."

7. Clinton splits with New Hampshire's governor on halting refugees

Asked about Democratic New Hampshire Gov. Maggie Hassan’s call for the federal government to stop accepting Syrian refugees, Clinton split with the popular governor, who has endorsed Clinton and is running for Senate in 2016.

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“I don't think a halt is necessary,” Clinton said, instead saying that the screening process should be “very tough” but that did not mean keeping all refugees from coming to the U.S. “We don't want to make it seem that we are turning into a nation of fear.”

O’Malley joined in too, saying “there are wider vulnerabilities than when it comes to refugees.”

8. O’Malley reminds everyone he’s younger than Clinton and Sanders

O’Malley went there. During a discussion on dealing with Assad and fighting ISIS, the former Maryland governor used his age as a campaign selling point. Clinton is 68, Sanders is 74, and O’Malley is 52.

“May I offer a different generation’s perspective on this?” O’Malley said, sparking audible shock from the audience.

9. We find out how Sanders has fun

As the debate moved deep into the weeds on the candidates' various economic plans, Clinton vowed not to raise taxes on the middle class. "No middle-class tax raises," she said, promising not to hike them on those making less than $250,000.

Sanders and O'Malley declined to make the same promise, and Sanders said Clinton was abandoning the Democratic Party's social legacy, "disagreeing with FDR on Social Security, disagreeing with LBJ on Medicare" and how to fund large social programs. Sanders mentioned paid family leave as an issue worth funding with a broad-based tax, though Clinton said she supported funding the proposal with taxes on the wealthy.

As the moderators kept the conversation going, Sanders quipped, "Now this is getting to be fun."

10. Clinton disappears

After the first break, the debate resumed with one glaring difference: Clinton was missing from the stage. As moderator David Muir stalled for time while delivering the next question, the cameras showed an empty center podium between Sanders and O'Malley.

Clinton walked back onstage to applause in the middle of that question. "I'm sorry," Clinton said, sounding slightly exasperated and sparking chuckles from the audience.

11. 'Everybody should'

Clinton wriggled out of a question about her ties to big business with a laugh line. When Muir asked if corporate America should “love Clinton,” she replied: "Everybody should." (The crowd laughed.) "I have said I want to be the president for the struggling, the striving, and successful."

When the question turned to Sanders (Would corporate America love a President Sanders?), the Vermont senator took a different route.

“No, I think they won’t,” Sanders said, again sparking laughter. “I don’t think I’m going to get a whole lot of campaign contributions from Wall Street.”

12. Sanders gives King Abdullah a shout-out

The king of Jordan got his second mention of the week in a presidential debate — but unlike Chris Christie in the GOP debate, Sanders got his name right.

In making his case on how to fight ISIS and direct America’s national security interests in the Middle East, the Vermont senator gave a shout-out to King Abdullah II of Jordan. Sanders said he didn’t believe in unilateral American action in the Middle East, pointing to Abdullah and saying the king said, "'We, the Muslims, should lead the effort on the ground,' and I think he's absolutely right.”

13. The role of the first lady — or gentleman

Clinton was asked whether her husband would take on the traditional role that first ladies have played if the former secretary of state and former President Bill Clinton make it back to the White House. After praising first ladies that came before and after her, the Democratic front-runner said, “I am probably still going to pick the flowers and the china for state dinners and things like that.” But Clinton added that she would still go to her husband for advice in the same way that other presidents have with their spouses.

Sanders praised Clinton for redefining the role of presidential spouse and talked about his wife's work with youth, while O'Malley said it was up to his wife whether she would continue her work as a district court judge in the event that he becomes president.

14. Many Bothans died to bring us this broadcast

Clinton had the last word Saturday night, and her sign-off was stranger than (science) fiction.

"Thank you, good night, and may the Force be with you," she said, an homage to the release of the new "Star Wars" movie.